(1) Field of the Invention
Exemplary embodiments of the present invention relate to a touch screen substrate, a method of manufacturing the touch screen substrate and a display panel including the touch screen substrate. More particularly, exemplary embodiments of the present invention relate to a touch screen substrate having substantially enhanced touch sensitivity, a method of manufacturing the touch screen substrate and a display panel including the touch screen substrate.
(2) Description of the Related Art
Generally, a liquid crystal display (“LCD”) panel includes a first substrate having a thin-film transistor (“TFT”) that drives a pixel, a second substrate facing the first substrate, and a liquid crystal layer interposed between the first and second substrates. To display an image on the LCD, liquid crystals of the liquid crystal layer control light transmittance through the liquid crystal layer by changing an alignment of the liquid crystals according an intensity of an electric field generated in the liquid crystal layer.
The LCD panel may be used as a touch panel operated according to pressure, from a user's touch, for example, that is applied thereto. In this case, the second substrate of the LCD panel may include a photo sensor and a switching element that controls the photo sensor. When pressure is applied to the LCD panel, the photo sensor absorbs incident light having a specific wavelength to generate a photo current. A central process unit connected to the LCD panel calculates a touch position based on a difference between the photo current and a dark current generated by the photo sensor before the incident light is irradiated onto the photo sensor.
Generally, electrical characteristics of the photo sensor are different from electrical characteristics of the switching element. Specifically, the switching element is merely turned on or off by a gate signal, while the photo sensor generates the photo current, having multiple values, based on the incident light. As a result, an enhancement of the sensitivity of the photo sensor for detecting the incident light is desired. Accordingly, various semiconductor materials have been developed in efforts to enhance the sensitivity of the photo sensor. However, maximizing and/or improving productivity of the liquid crystal display panel is limited, due to high costs for research and development of the various semiconductor materials.